(1) Field of the Invention
The present invention relates to a cooking device, such as a convection oven or a hot-air-impact oven, for cooking a cooking target with heat.
(2) Description of Related Art
A cooking device 100 known as a convection oven for cooking a cooking target with heat is typically constructed as shown in FIG. 17. FIG. 17 is a diagram showing an outline of the construction of such a conventional cooking device 100. In FIG. 17, the cooking device 100 is composed of: a box-shaped member 2 that is thermally insulated; a heating chamber 3 that is formed inside the box-shaped member 2 to permit a cooking target to be placed therein; heating means 4 that heats the cooking target placed in the heating chamber 3; and blowing means 5. The blowing means 5 is provided with a blowing machine 54, which is composed of: a centrifugal fan 51; a drive motor 52 that drives the centrifugal fan 51; and a fan casing 53 that communicates with the heating chamber 3 through a suction port 6 and a blowoff port 7 and on which the centrifugal fan 51 is pivoted. The hot air heated by the heating means 4 is introduced into the heating chamber 3 by the blowing means 5 so that the air inside the heating chamber 3 is heated and circuited in such a way as to make the temperature inside the heating chamber 3 uniform and thereby cook the cooking target with heat.
Conventional cooking devices of this type are disclosed, for example, in Japanese Utility Model Published No. H6-23841 and Japanese Patent Application Laid-Open No. 2000-329351. The cooking devices disclosed in these publications both adopt a cooking method whereby the air inside a heating chamber is heated and circulated in such a way as to make the temperature inside the heating chamber uniform and thereby cook a cooking target with heat (hereinafter, this method will be referred to as the hot-wind-circulation method).
This cooking method, however, has the disadvantage of requiring rather a long time for cooking. The time required for cooking can be shortened by increasing the rotation rate of the centrifugal fan so as to increase the wind volume, and by increasing the amount of heat generated by the heater. This, however, results in not only greatly increased power consumption but also greatly increased noise, which constitutes a critical drawback.
On the other hand, Japanese Patent Application Laid-Open No. H9-503334 discloses a cooking device that adopts, instead of the hot-wind-circulation method mentioned above, a cooking method whereby the air heated by heating means is blown directly at a cooking target so as to cook the cooking target with heat (hereinafter, this method will be referred to as the hot-air-impact method).
The hot-wind-circulation method and the hot-air-impact method differ from each other in that, whereas the former operates blowing means for the purpose of making the temperature inside a heating chamber uniform and, by using the thus uniformized heat, applies heat uniformly to a cooking target, the latter blows hot air at a cooking target from a predetermined direction and, by using the hot air, cooks the cooking target with heat.
In the hot-air-impact method, cooking is achieved by making the hot air heated by a heater hit a cooking target at a high speed by the action of a blowing machine. This helps greatly reduce the time required for cooking without unduly increasing the power consumption by the heater.
Indeed, the hot-air-impact method is very suitable for the cooking of a chunk of meat is not interfered with by the wind pressure of a hot air impact. However, the hot-air-impact method is unsuitable for the cooking of sponge cake or the like, i.e., a cooking target that is cooked by producing bubbles therein, or a cooking target that contains much air. The reason is that, inconveniently, the wind pressure of a hot air impact causes such a cooking target to become unacceptably deformed, unduly hard, or charred at the surface, and thereby interferes with the cooking thereof.
An object of the present invention is to provide a cooking device that, alone, permits the use of a plurality of cooking methods so as to be capable of cooking any type of cooking target.